Shape memory alloy-based moment connections with superior self-centering properties

Abstract

Superelastic shape memory alloys (SMAs) have the potential to create a spontaneous recentering mechanism on the connections of a structural system under seismic actions, which results in mitigation of the damage in the main structural members. In this article, innovative types of steel beam-to-column moment connections incorporating SMA bolts and plates are introduced and studied through a numerical approach. First, SMA bolted end-plate connection model is produced and analyzed by means of the finite element method to validate the numerical analysis against the prior experimental results. Then, the performance of eleven different end-plate moment connection models subjected to cyclic loading is investigated. By selecting the lower values for the moment capacity based on bolts strength in comparison to the flexural resistance of the beam, the plastic hinge is transferred from the beam section to the beam-column interface. Hence, employing superelastic materials at the connection interface could be potentially effective in providing the desired self-centering effect in the connection. To this end, the impact of utilizing superelastic SMA bolts and end-plates instead of using the conventional structural steel on the overall cyclic response of the connections is evaluated in this study. Results show that extended end-plate connections equipped with SMA bolts and end-plates, if properly proportioned and detailed, not only exhibit a clear reduction in the residual drifts after a seismic event, but also can meet the ductility requirements with good energy dissipation and sufficient stiffness.

Limit state behavior and response sensitivity analysis of endplate steel connections with shape memory alloy bolts

“…Prior research (e.g. Farmani and Ghassemieh, 2016; Yam et al, 2015) provides valuable findings on the effect of design factors on the behavior of SMA-based steel moment connections; however, the study is based on a one-factor-at-a-time (OFAT) approach. In OFAT, one factor is successively varied over its range, while the other factors are kept constant.…”

“…SMAs are a special class of metallic alloys that can undergo large recoverable strains of up to 13% (Tanaka et al, 2010). SMA self-centering braced frames (Gao et al, 2016; Miller et al, 2012; Xu et al, 2016), self-centering reinforced concrete beams using SMA fibers (Shajil et al, 2013), and SMA-based steel connections (Fang et al, 2014, 2015a; Farmani and Ghassemieh, 2016; Wang et al, 2017) are examples of research on the applications of SMA materials in earthquake-resistant structures.…”

Active Reinforcing Fiber of Cementitious Materials Using Crimped NiTi SMA Fiber for Crack-Bridging and Pullout Resistance

“…Straight SMA fiber is seldom used because it only has frictional resistance, which is too weak in comparison with anchorage resistance [ 30 , 31 , 32 ]. Previous studies have suggested various shapes of SMA fibers, such as L-, N-, dog-bone, and paddle-shaped ones [ 33 , 34 , 35 , 36 ]. Of these types, the paddled SMA fiber is the most effective to provide end-anchoring action, and thus it is the most appropriate for crack-bridging [ 10 ].…”

Experimental Investigation on the Behavior of Bracing Damper Systems by Utilizing Metallic Yielding and Recentering Material Devices

“…Although the conventional bracing damper system has an excellent ability not only to absorb the external impact but also to diminish the structural vibration, it has the disadvantage of requiring additional maintenance due to the residual deformation caused by the lack of recentering capability [10][11][12][13][14]. Accordingly, this paper proposes new bracing damper systems that can e ectively reduce the residual displacement by installing seismic retro t devices to enhance the recentering capability of the bracing member.…”